Milk V Duo Bare Metal GPIO Driver

Implementation Description:

The following implementation contains the MilkV_GPIO class, which provides the ability to manage General Purpose Input/Output (GPIO) ports on the Milk-V platform using the /dev/mem address space. The class provides methods for initializing pins, reading and writing pin states, managing interrupts, and enabling/disabling debounce functionality. The easiest way to compile that library is to clone duo-examples repository, follow the instruction to setup compiler and environment than add that project to examples.

Functionality and Function Descriptions:

1. Constructor and Destructor:

   • Constructor: Initializes the MilkV_GPIO object with the specified GPIO port and pin number.
     • Parameters:
       • GPIOPort port: The GPIO port (GPIOPort0, GPIOPort1, GPIOPort2, GPIOPort3, PowerGPIO).
       • uint32_t pinNumber: The pin number.
   • Destructor: Clears the GPIO list and releases resources.

2. Initialization:

   • init(GPIODirection pinDirection): Initializes the GPIO pin as either input or output.
     • Parameters:
       • GPIODirection pinDirection: The direction of the pin (GPIOInput, GPIOOutput).

3. Pin Operations:

   • writePin(bool pinState): Sets the pin state to high or low.
     • Parameters:
       • bool pinState: The state of the pin (true - high, false - low).
   • readPin(void): Reads the state of the pin (high or low).
     • Returns: The state of the pin (1 - high, 0 - low).

4. Interrupt Management:

   • enableInterrupt(void): Enables interrupts for the pin.
   • disableInterrupt(void): Disables interrupts for the pin.
   • enableInterruptMask(void): Enables the interrupt mask for the pin.
   • disableInterruptMask(void): Disables the interrupt mask for the pin.
   • setInterruptLevelType(IntLevelType levelType): Sets the interrupt level type (level sensitive or edge sensitive).
     • Parameters:
       • IntLevelType levelType: The interrupt level type (LevelSensitive, EdgeSensitive).
   • setInterruptPolarity(IntPolarity polarity): Sets the interrupt polarity (active low or high).
     • Parameters:
       • IntPolarity polarity: The interrupt polarity (ActiveLow, ActiveHigh).

5. Debounce:

   • enableDebounce(void): Enables the debounce function for the pin.
   • disableDebounce(void): Disables the debounce function for the pin.

6. Interrupt Status:

   • getIntStatus(void): Returns the interrupt status.
   • getRawIntStatus(void): Returns the raw interrupt status.

Structures and Global Variables:

1. Structure GPIOReg:

   • This structure holds control registers for the GPIO port.

2. Global Variables:

   • sGPIOList: A static list of pointers to GPIOReg structures representing GPIO ports.

Helper Functions:

1. getGPIOAccess(void):
   • This function gains access to the GPIO address space using mmap and opens /dev/mem.
   • Allocates memory for the GPIO registers and adds pointers to the sGPIOList.

Flow diagram:

Example code of usage MilkV GPIO Driver inside blink.cpp file.